All-Optical and Thermal Tuning of a Bragg Grating Based on Photosensitive Composite Structures Containing Liquid Crystals

We report on the fabrication and characterization of a tunable filtering effect, observed in a waveguide grating made of alternated strips of photocurable polymer and a mixture of azo-dye doped liquid crystal. The grating is sandwiched between two borosilicate glasses, one of which includes an ion-exchanged channel waveguide, which confines the optical signal to be filtered. We analyze the effects of a low power visible, pump light beam that hits the sample and temperature effects. Both effects are investigated experimentally. The application of the pump light allowing the filtered wavelength to be tuned over a 6.6 nm range, while a temperature variation of 4 degrees C, implies a tuning of 14 nm.